In large scale laminating systems, it is known to provide upper and lower feed rollers for continuously supplying a strip or sheet of laminating film which has a heat sensitive adhesive on a product-facing surface thereof. Such laminating films are well known in the art as polyethylene films which are transparent and which have a heat sensitive adhesive thereon which joins to the product to be laminated and also to the opposite facing thin film so as to form a packet. In the large scale laminating systems, the laminating film is fed continuously and after the laminating of a continuous product, the product is slit transversely to the running direction of the laminated product and/or along the direction of travel so as to cut the laminated product into individual units such as I.D. cards.
With such systems, it is also known to provide a heating shoe or member positioned adjacent each of the laminating rollers such that the continuous rolls of film being supplied from the supply rollers pass over a heating surface of the shoe just prior to entering a nip between the upper and lower laminating rollers. These shoes heat the laminating film to a desired temperature just prior to the pressure laminating in the nip between the two laminating rollers.
Previously, as the film is dragged over the hot shoe, miniscule irregularities in the shoe surface would scratch the film and introduced obvious marking to the detriment of ultimate use. While the functional use of the finished laminate was not greatly affected, the aesthetics were such that the commercial viability of such large scale laminating systems was impaired.
In addition to the scratching problem, the dragging of the film over the shoes especially at high speed and elevated temperatures consistently produces a high pitched squeal. This squeal at times becomes intolerable.
Attempts have been made to solve the squealing problem by altering the tension on the webs or dampening. Neither approach was successful.